"""Generic linux daemon base class for python 3.x."""
# pylint: disable=multiple-imports

import sys, os, time, atexit, signal


class Daemon:
    """A generic daemon class.

	Usage: subclass the daemon class and override the run() method.
    """

    def __init__(self, pidfile, fifofile):
        self.pidfile = pidfile
        self.fifofile = fifofile

    def daemonize(self):
        """Deamonize class. UNIX double fork mechanism."""

        try:
            pid = os.fork()
            if pid > 0:
                # exit first parent
                sys.exit(0)
        except OSError as err:
            sys.stderr.write("fork #1 failed: {0}\n".format(err))
            sys.exit(1)

        # decouple from parent environment
        os.chdir("/")
        os.setsid()
        os.umask(0)

        # do second fork
        try:
            pid = os.fork()
            if pid > 0:

                # exit from second parent
                sys.exit(0)
        except OSError as err:
            sys.stderr.write("fork #2 failed: {0}\n".format(err))
            sys.exit(1)

        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        si = open(os.devnull, "r")
        so = open(os.devnull, "a+")
        se = open(os.devnull, "a+")

        os.dup2(si.fileno(), sys.stdin.fileno())
        os.dup2(so.fileno(), sys.stdout.fileno())
        os.dup2(se.fileno(), sys.stderr.fileno())

        # write pidfile
        atexit.register(self.delpid)

        os.mkfifo(self.fifofile)  # pylint: disable=no-member

        pid = str(os.getpid())
        with open(self.pidfile, "w+") as f:
            f.write(pid + "\n")

        workdir = os.getenv("AZ_BATCH_TASK_WORKING_DIR","/tmp")
        sys.stdout = open(os.path.join(workdir,"sc-out.txt"),"a+")
        sys.stderr = open(os.path.join(workdir,"sc-err.txt"),"a+")
        print("daemonized >>>>>>>>>>>"); sys.stdout.flush()

    def delpid(self):
        " clean up"
        try:
            os.remove(self.pidfile)
        except: 
            print("failed to remove pidfile"); sys.stdout.flush()
            raise RuntimeError("failed to remove pidfile")
        else:
            print("removed pidfile"); sys.stdout.flush()
        try:
            os.remove(self.fifofile)
        except: 
            print("failed to remove fifofile"); sys.stdout.flush()
            raise RuntimeError("failed to remove pidfile")
        else:
            print("removed fifofile"); sys.stdout.flush()

        

    def start(self):
        """Start the daemon."""

        # Check for a pidfile to see if the daemon already runs
        try:
            with open(self.pidfile, "r") as pf:

                pid = int(pf.read().strip())
        except IOError:
            pid = None

        if pid:
            message = "pidfile {0} already exist. " + "Daemon already running?\n"
            sys.stderr.write(message.format(self.pidfile))
            sys.exit(1)

        # Start the daemon
        self.daemonize()
        self.run()

    def stop(self):
        """Stop the daemon."""

        # Get the pid from the pidfile
        try:
            with open(self.pidfile, "r") as pf:
                pid = int(pf.read().strip())
        except IOError:
            pid = None

        if not pid:
            message = "pidfile {0} does not exist. " + "Daemon not running?\n"
            sys.stderr.write(message.format(self.pidfile))
            return  # not an error in a restart

        # Try killing the daemon process
        try:
            while 1:
                os.kill(pid, signal.SIGTERM)
                time.sleep(0.1)
        except OSError as err:
            e = str(err.args)
            if e.find("No such process") > 0:
                if os.path.exists(self.pidfile):
                    os.remove(self.pidfile)
                if os.path.exists(self.fifofile):
                    os.remove(self.fifofile)
            else:
                print(str(err.args))
                sys.exit(1)

    def restart(self):
        """Restart the daemon."""
        self.stop()
        self.start()

    def run(self):
        """You should override this method when you subclass Daemon.
		
		It will be called after the process has been daemonized by 
		start() or restart()."""
